# 集合无序

bri = set(['a', 'c', 'b', 'd'])
print(bri)
print('a' in bri)
print(bri)

bric = bri.copy()
print(bric)
bric.add('g')
print(bric)
print(bric.issubset(bri))
print(bric.issuperset(bri))

bri.remove('b')
print(bri & bric)

